Air-cooled refrigerator, and control method, control system and controller for defrosting thereof

ABSTRACT

An air-cooled refrigerator and a control method, a control system and controller for defrosting thereof are provided. The high-temperature air of the air-cooled refrigerator exchanges heat with the evaporator in the air duct and is sent into a refrigerating compartment through the operation of a fan; when the evaporator is gradually frosted, the heat-exchanged air suffers the resistance from the frosts on the evaporator during the flow and the fan slows down. Based on this principle, the fan speed can directly correspond to the frost accumulation mass of the evaporator. The actual frost accumulation mass of the evaporator can be directly determined by determining the fan speed. When the fans peed is decreased to a certain low speed, it means that there is much frost on the evaporator and the defrosting needs to be started timely. As a result, the problems of large energy consumption and poor fresh-keeping effect caused by the traditional control method of defrosting in advance or delayed defrosting can be solved, and the energy-saving and fresh-keeping effects of the air-cooled refrigerator can be improved.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to Chinese patent application No. 2018102824146 filed on Apr. 2, 2018, entitled “Air-cooled refrigerator and Control Method, Control System and Controller for Defrosting thereof”, which is incorporated herein by reference in its entirety.

BACKGROUND Technical Field

The embodiments of the present application relate to the field of defrosting control, in particular to a control method for defrosting an air-cooled refrigerator, a control system and a controller for defrosting an air-cooled refrigerator, and an air-cooled refrigerator.

Description of the Related Art

Air-cooled refrigerators, also referred to as frost-free refrigerators, are configured to refrigerate with air. When high-temperature air flows through a built-in evaporator, the high-temperature air directly exchanges heat with the evaporator with a low temperature, the temperature of the air is reduced, and the cooled air is blown into the refrigerator through a fan for refrigeration.

Since there is always water vapor in the air, water vapor will condense when it gets cold. During the process of continuous heat exchange, the water vapor will be gradually frosted on the evaporator. In order to promote the functional operation of the evaporator, it is necessary to defrost the evaporator. At present, there are many conditions for starting defrosting: a control method for defrosting a refrigerator provided by CN106288613A determines whether defrosting is needed based on the cumulative operation time of a compressor which operates multiple times; fan control methods provided by CN106091566A and CN107477973A determine whether defrosting is needed based on a temperature; CN106403487A determines whether defrosting is needed according to the door-opening time and other factors. In other technologies, the combination of ambient temperature and humidity is used as the defrosting determination condition. Among all the determination schemes above, the frost accumulation mass is estimated based on empirical values, and defrosting is started based on the estimated amount. However, these estimation methods are not suitable for the actual application of refrigerators in many cases. For example, different users' usage habits, unknown type of food that users put when opening the door each time and unknown amount of food may result in completely different actual moisture content and thus the frosting of the evaporator varies greatly. The determination conditions in the art often have the following shortcomings.

1. Defrosting is performed in advance. When the actual frost accumulation mass is not large (for example, the user opens the door for a long time, the actual frost accumulation mass may not be too much because no foods are put when the door is opened), determining the frost accumulation mass based on the opening duration will inevitably cause defrosting in advance and power consumption increase. Meanwhile, the temperature inside the refrigerator will rise due to heating when the defrosting is performed, so the temperature of the food in the refrigerator will rise and the fresh-keeping effect will be weakened.

2. Defrosting is delayed. When the actual frost accumulation mass is large (if the user opens the door for a short time, too much food with high moisture content are put, the actual frost accumulation mass will be too much), it is determined that the defrosting condition is not satisfied, and it is still waiting more door-opening time, running time or other conditions. It will increase the frost accumulation mass and weaken the refrigerating effect as well as cause serious complaints from users about the refrigerator not refrigerating. Due to the poor cooling effect and low efficiency, energy consumption will also increase. The fresh-keeping effect is also greatly reduced.

BRIEF SUMMARY Technical Problems to be Solved

The embodiments of the application are to provide a control method for defrosting an air-cooled refrigerator, a control system and a controller for defrosting an air-cooled refrigerator, and an air-cooled refrigerator, which solve at least the problem that the defrosting timing of the air-cooled refrigerator does not correspond to the actual frosting of an evaporator.

Technical Solutions

In order to solve at least the technical problem above, the present application provides a control method for defrosting an air-cooled refrigerator, which includes: collecting a fan speed R during stable operation of a refrigerator; determining whether the fan speed R is less than or equal to a preset speed R_(min); performing defrosting operation when the fan speed R is less than or equal to a preset speed R_(min).

In this technical solution, the actual frost accumulation mass of the evaporator is inferred from the fan speed based on the principle that the frosting of the evaporator generates resistance to an airflow and the fan speed decreases, and whether defrosting is needed is determined according to the frost accumulation mass, and defrosting operation can be done in time. The frosting operation is also avoided under non-defrosting demand and energy consumption is saved.

In some embodiments, a heater is employed to defrost during the defrosting operation.

In this technical solution, the heater is arranged at the bottom of the evaporator, and the evaporator is defrosted by heat directly, and the melted frost is drained away by a drain pipe to improve the defrosting efficiency.

In some embodiments, a method of collecting the fan speed includes allowing the fan to operate at a rated voltage, and determining the fan speed by detecting feedback signals of an electric control loop where the fan is located.

In this technical solution, the fan speed is determined according to the operation information of the fan and thus the actual operation of the fan is effectively controlled, and the accuracy of the frost accumulation mass determination of the evaporator is improved.

In some embodiments, after the defrosting operation is performed, the control method further includes: collecting the temperature of the evaporator; determining whether the temperature of the evaporator reaches a preset defrosting temperature; and stopping the defrosting when the temperature of the evaporator reaches a preset defrosting temperature.

In this technical solution, it is determined whether the evaporator has been defrosted completely based on whether the evaporator has no frost or is higher than a certain temperature after the defrost is completed, and the defrosting is terminated timely to save energy consumption.

In some embodiments, before collecting the fan speed R during the stable operation of the refrigerator, the control method further includes: collecting a fan speed R_(before) and a fan speed R_(after) of the refrigerator before and after a preset time period; determining whether the absolute value of the difference between the fan speed R_(before) and the fan speed R_(after) is less than or equal to ΔR; when the absolute value of the difference between the fan speed R_(before) and the fan speed R_(after) is less than or equal to ΔR, determining that the refrigerator is operating stably.

In the refrigeration operation of the refrigerator provided by the technical solution, the process determination from the start of the refrigerator to the stable operation thereof provides a more accurate determination environment for the subsequent determination of the frost accumulation mass of the evaporator according to the fan speed, and improves the accuracy of determination.

The embodiment of the present application also provides a controller that executes the control method for defrosting an air-cooled refrigerator, which includes: a data receiver configured to acquire the temperature of an evaporator and fan speeds of the refrigerator in different states; a determiner configured to perform the control method above and determine whether the refrigerator needs to be defrosted according to the fan speed or determine whether the refrigerator stops the defrosting operation according to the temperature of the evaporator; a signal sender configured to send determination results made by the determiner to a defrosting assembly of the refrigerator, wherein the determination results include starting defrosting, without starting defrosting, continuing defrosting, and stopping defrosting.

In this technical solution, multiple functional modules are provided to perform corresponding operations of the control method for defrosting an air-cooled refrigerator. The actual frost accumulation mass of the evaporator is inferred from the fan speed based on the principle that the frosting of the evaporator generates resistance to an airflow and the fan speed decreases, and whether defrosting is needed is determined according to the frost accumulation mass, and defrosting operation can be done in time. The frosting operation is also avoided under non-defrosting demand and energy consumption is saved.

The embodiment of the present application also provides a control system for defrosting an air-cooled refrigerator, which includes: a fan, a defrosting assembly, and the controller, wherein the fan is disposed in an air duct of a refrigerator body; the controller is connected with the fan and the defrosting assembly through an electric control circuit respectively, and the controller detects the fan speed, and determines whether the defrosting assembly is activated according to the fan speed.

This technical solution corresponds to the above-mentioned control method for defrosting the air-cooled refrigerator. The fan runs in the air duct, the defrosting assembly is disposed on the evaporator or provides defrosting heat for the evaporator, and the controller is configured to control the fan and the defrosting assembly. Through the effective control of the control system, the actual frost accumulation mass of the evaporator is inferred from the fan speed, and whether defrosting is needed is determined according to the frost accumulation mass, and defrosting operation can be done in time. The frosting operation is also avoided under non-defrosting demand and energy consumption is saved.

In some embodiments, the control system for defrosting the air-cooled refrigerator further includes: an evaporator sensor electrically connected with the controller and configured to detect the temperature of the evaporator. During the defrosting operation performed by the defrosting assembly, the controller determines whether the defrosting assembly stops the defrosting operation according to the temperature of the evaporator detected by the evaporator sensor.

In this technical solution, the temperature of the evaporator during and after defrosting is detected by the evaporator sensor, and the defrosting operation is terminated timely. It is determined whether the evaporator has been defrosted completely based on whether the evaporator has no frost or is higher than a certain temperature after the defrost is completed, and the defrosting is terminated timely to save energy consumption.

In some embodiments, the defrosting assembly includes a heater arranged at the bottom of the evaporator.

The present application also provides a computer device, including a memory, a processor, and computer programs stored on the memory and capable of running on the processor, and the processor executes the control method when the computer programs is executed.

The present application also provides a computer-readable storage medium on which computer programs is stored, and the control method is implemented when computer programs are executed by the processor.

The present application also provides an air-cooled refrigerator, which includes an air duct of a refrigerator body, a compressor, a condenser, a capillary tube, an evaporator, and the control system, wherein the compressor, the condenser, the capillary tube, and the evaporator constitutes a refrigerant circulation loop; the evaporator is disposed in the air duct of the refrigerator body, and the evaporator is located upstream of the fan on the air flow path of the air duct of the refrigerator body.

In this technical solution, a refrigerator including any of the above control systems can defrost the evaporator of the refrigerator at a more optimized frosting time under refrigerating conditions, that is, to avoid delay in defrosting and starting of defrosting when there is little frost accumulation mass or no icing, which reduces energy consumption and is more suitable for the actual use of the refrigerator.

Beneficial Effects

According to the technical solutions provided by the embodiments of this application, the high-temperature air of the air-cooled refrigerator exchanges heat with the evaporator in the air duct and is sent into a refrigerating compartment through the operation of the fan; when the evaporator is gradually frosted, the heat-exchanged air suffers the resistance from the frosts on the evaporator during the flow and the fan slows down. Based on this principle, the fan speed can directly reflect the frost accumulation mass of the evaporator. The actual frost accumulation mass of the evaporator can be directly determined by determining the fan speed. When the fans peed is decreased to a certain low speed, it means that there is much frost on the evaporator and the defrosting needs to be started timely. As a result, the problems of large energy consumption and poor fresh-keeping effect caused by the traditional control method of defrosting in advance or delayed defrosting can be solved, and the energy-saving and fresh-keeping effects of the air-cooled refrigerator can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic flow chart showing a process of determining the defrosting of the evaporator based on a fan speed according to an embodiment of the application;

FIG. 2 is a schematic flow chart of a control method for defrosting an air-cooled refrigerator according to an embodiment of the application;

FIG. 3 is a schematic structure diagram of a controller according to an embodiment of the application; and

FIG. 4 is a schematic structure diagram of a control system for defrosting an air-cooled refrigerator according to an embodiment of the application.

DETAILED DESCRIPTION

The specific embodiments of the present application are further described in detail below with reference to the drawings and embodiments. The following examples are intended to illustrate the application, but are not intended to limit the scope of the application.

In the description of embodiments of the present application, it is to be noted that unless explicitly stated and defined otherwise, the terms “installed,” “connected with,” and “connected” shall be understood broadly, for example, it may be either fixedly connected or detachably connected, or can be integrated; it may be mechanically connected, or electrically connected; it may be directly connected, or indirectly connected through an intermediate medium and the communication between the interior of two elements. “First”, “second”, “third”, and “fourth” do not represent any sequence relationship, but are just for the convenience of description. The specific meanings of the terms above in embodiments of the present application can be understood by a person skilled in the art in accordance with specific conditions. “Current” means a moment when certain action is performed, multiple currents appear in the text, all of which are recorded in real time over time.

In order to solve the problem that the defrosting timing of the air-cooled refrigerator does not correspond to the actual frosting of an evaporator, the embodiments of the application are directed to a control method for defrosting an air-cooled refrigerator, a control system and a controller for defrosting an air-cooled refrigerator, and an air-cooled refrigerator.

The products and methods will be described in detail below through basic designs, extended designs and replacement designs.

During the refrigerating process of the air-cooled refrigerator, the evaporator maintains a low temperature to provide refrigerating capacity. In the initial stage, the evaporator has less frost and thus has less resistance to the flow of air, the air flows in the air duct smoothly, and the fan maintains a certain speed. As the refrigeration time prolongs or the moisture load of the foods increases, the frosts on the evaporator will be accumulated, the evaporator is clogged heavily, the wind resistance of the air duct will increase, and the fan speed will decrease since the voltage supplied to the fan by the motherboard will remain unchanged. Therefore, the fan speed can reflect the actual amount of frost accumulated on the evaporator during refrigeration operation, referred to as “frost accumulation mass” of the evaporator.

Based on the foregoing principles, an embodiment of the present application provides a control method for defrosting an air-cooled refrigerator, which determines the frost accumulation mass of an evaporator according to a fan speed, and then determines whether the evaporator needs to be defrosted, as shown in FIG. 1, which includes:

step 01: collecting the fan speed R during stable operation of the refrigerator;

the corresponding relation between the fan speed and the frost accumulation mass of the evaporator is established under the condition of stable operation of the refrigerator, and the influence of any abnormal operation on the fan speed and the frost accumulation mass of the evaporator is excluded;

step 02: determining whether the fan speed R is less than or equal to the preset speed R_(min);

After the evaporator is frosted, the evaporator will generate resistance to the flow of the air, and the fan speed will be affected. As the frost accumulation mass increases, the fan speed will gradually decrease. When the fan speed decrease to a preset speed R_(min), it indicates that the evaporator has sufficient frost accumulation mass. Thus, defrosting can be performed timely, that is, if the determination result is “yes,” e.g., the fan speed is less than or equal to R_(min), the defrosting operation is executed; if the determination result is “no,” e.g., the fan speed is greater than R_(min), then the process returns to step 01.

Steps 01 and 02 give the operation method of effective defrosting based on the actual frost accumulation mass of the evaporator, which effectively solves the problems of high energy consumption and poor fresh-keeping effect caused by early defrosting or late defrosting in the traditional control method, and improves the energy-saving and fresh-keeping effects of the air-cooled refrigerator.

A more specific control method is given below in conjunction with the overall process for defrosting the air-cooled refrigerator, as shown in FIG. 2.

The control method includes step 110: collecting a fan speed R_(before) and a fan speed R_(after) of the refrigerator before and after a preset time period;

determining whether the refrigerator is operating normally and stably based on the change of the fan speed in a short period of time, wherein a few seconds, such as 5 seconds, can be selected as a preset time period; and

since the refrigerator is in different working states, for example, in an unstable operation state, a defrosting state, a state of determining whether a defrosting is needed, etc., the fan speed is collected in real time. The operation of the fan is controlled by the main control board (also called the controller) of the refrigerator. Both the fan and the main control board are connected to the electric control loop. The fan operates at the rated voltage. The operation signal of the fan is transmitted back to the main control board through the electric control loop and the fan speed is determined after being analyzed by the main control board. This embodiment only provides one example method for collecting the fan speed. In other embodiments, various methods provided in the prior art may be used to collect the fan speed.

The control method includes step 112: determining whether the absolute value of the difference between the fan speed R_(before) and the fan speed R_(after) is less than or equal to ΔR;

if the determination result is yes, e.g., less than or equal to ΔR), determining that the refrigerator is operating stably; and

if the determination result is no, e.g., greater than ΔR, continuing to repeat step 110.

Steps 110 and 112 are used to determine whether the refrigerator is operating stably. Once it is determined that the refrigerator is operating stably, the process proceeds to determine the frost accumulation mass of the evaporator.

The control method includes step 114: collecting the fan speed R during stable operation of the refrigerator;

step 116: determining whether the fan speed R is less than or equal to the preset speed R_(min);

if the determination result is yes, e.g., less than or equal to R_(min), executing the defrosting operation, activating the defrosting assembly to defrost the evaporator, and the melted frost is drained through a drain pipe; and

if the determination result is no, e.g., greater than R_(min), returning to step 114 and continuing to collect the fan speed in real time.

There are multiple defrosting treatment methods, such as defrosting by return air and defrosting by heating. In this embodiment, a heater disposed on the evaporator is used for defrosting.

It should be noted that steps 114 and 116 are specific steps for determining the frost accumulation mass of the evaporator and determining whether the evaporator needs to be defrosted. These steps can be performed in real time in the refrigerating mode of the air-cooled refrigerator, or can be collected and determined at a preset frequency.

The control method includes step 118, in the defrosting operation, collecting the temperature T of the evaporator;

step 120: determining whether the temperature T of the evaporator reaches a preset defrost temperature T_(preset);

stopping defrosting if the determination result is yes, e.g., reach T_(preset); and

continuing defrosting if the determination result is no, e.g., T_(preset) not reached.

The temperature of the unfrosted or defrosted evaporator is usually higher than a certain temperature, so it is determined whether the evaporator has been defrosted completely, and the defrosting is terminated timely to save energy consumption. Therefore, whether to terminate the defrosting of the evaporator is determined by the change in the temperature of the evaporator. On the other hand, it should be noted that the temperature of the evaporator drops after being frosted and can be collected in real time by the evaporator temperature sensor, but the change in the temperature of evaporator cannot reflect the frost accumulation mass and the thickness of the accumulated frost.

This technology provides a control method for determining the frost accumulation mass of the evaporator based on the fan speed, and then controlling the defrosting operation. This method can also be configured to determine the defrosting in combination with a number of times and duration the door is opened and closed, number and type of foods stored in the refrigerator and the change in the temperature of the refrigeration compartment.

Further, a controller that executes the above control method for defrosting the air-cooled refrigerator is provided. As shown in FIG. 3, the controller can be loaded into an electric control board of the refrigerator in the form of a software program or a hardware device.

The controller includes: a data receiver, a determiner, and a signal sender, wherein the data receiver and the signal sender are all connected with the determiner. The data receiver configured to acquire the temperature of an evaporator and fan speeds of the refrigerator in different states; a determiner configured to, according to the control method above, determine whether the refrigerator needs to be defrosted according to the fan speed or determine whether the refrigerator stops the defrosting operation according to the temperature of the evaporator; a signal sender configured to send determination results made by the determiner to a defrosting assembly of the refrigerator, wherein the determination results include starting defrosting, without starting defrosting, continuing defrosting, and stopping defrosting.

The fan speed includes the speed values collected in real time under various states in steps 110-120.

In some embodiments, the data receiver, the determiner, and the signal sender can be split into smaller unit components according to function or structure design to refine the function of each unit component. In some embodiments, the determiner can be implemented as a part of control circuit or on-board computer of the main control board, or by the controller or processer of a fridge.

The embodiment of the present application also provides a control system for defrosting an air-cooled refrigerator as shown in FIG. 4, which includes: a fan disposed in an air duct of a refrigerator body, a defrosting assembly, and the controller, wherein the controller is connected with the fan and the defrosting assembly through an electric control circuit respectively, and the controller detects the fan speed, and determines whether the defrosting assembly is activated according to the fan speed.

In an embodiment of the present application, an evaporator sensor is electrically connected to the controller for detecting the temperature of the evaporator; during the defrosting operation of the defrosting assembly, the controller determines whether the defrosting assembly stops the defrosting operation according to the temperature of the evaporator detected by the evaporator sensor.

The defrosting assembly includes a heater arranged at the bottom of the evaporator, and the melted frost of the evaporator flows into the water receiving box under the evaporator, and then is drained with a drain pipe.

The embodiment of the present application also provides a computer device, including a memory, a processor, and computer programs stored on the memory and capable of running on the processor, and the processor executes the control method when the computer programs is executed.

In this technical solution, the computer programs that executes the above described control method for defrosting an air-cooled refrigerator is stored in the memory. When the processor executes the computer programs, it can accurately determine the frosting of the evaporator and defrost in time.

The embodiment of the present application also provides a computer-readable storage medium on which computer programs is stored, and the control method is implemented when computer programs are executed by the processor.

In this technical solution, the processor needs to use computer programs to implement the control method of defrosting the air-cooled refrigerator, and this computer programs needs to be stored in a computer-readable medium. This computer-readable medium ensures that the computer programs can be executed by the processor, thereby accurately determining the degree of frosting of the evaporator in the refrigerator, and avoiding the situation of defrosting without frost or delayed defrosting.

An embodiment of the application also provides an air-cooled refrigerator, which includes an air duct of a refrigerator body, a compressor, a condenser, a capillary tube, an evaporator and a control system;

The compressor, the condenser, the capillary tube, and the evaporator constitutes a refrigerant circulation loop; the evaporator is disposed in the air duct of the refrigerator body, and the evaporator is located upstream of the fan on the air flow path of the air duct of the refrigerator body.

When the compartment is refrigerated, the compressor runs. After the refrigerant is condensed, it becomes a low-temperature and low-pressure refrigerant through the throttling of the capillary tube, and then flows through the evaporator to exchange heat, and thus the temperature of the evaporator is decreased, the freezing fan in the air duct is also operating and the refrigerating capability of the evaporator is brought out inside the refrigerator. The evaporator will absorb the moisture in the refrigerator simultaneously to form frost during the refrigerating process and the frost adheres to the surface of the fins and pipes of the evaporator. During the refrigerating process, the evaporator maintains low temperature to provide refrigerating capacity, and the refrigerating fan operates and rotates at a rated voltage supplied through the main control board, and allows the return air to flow through the evaporator for heat exchange and sends it out into the refrigerator through the air outlet. In the initial stage, the evaporator has less frost and thus has less resistance and less wind resistance exists in the air duct, and the fan maintains a certain speed. As the refrigeration time prolongs or the moisture load of the foods increases, the frosts on the evaporator will become more, the evaporator is clogged heavily, the wind resistance of the air duct will increase, and the fan speed will be decreased since the voltage supplied to the fan by the motherboard will remain unchanged. The fan speed is fed back to the main board through the electronic control loop and it means that defrosting is needed when the main board senses that the fan speed drops to a certain low speed, When the defrosting timing is reached, the defrosting heater at the bottom of the evaporator starts heating, so that the frost on the evaporator is melted into water and flows out to the outside of the refrigerator through the drain pipe to volatilize. When the defrosting sensor senses the defrosting exit temperature, defrosting by heating is terminated and the defrosting is completed.

In the embodiment of the application, the actual frost accumulation mass of the evaporator in the refrigerator is determined through the control rule and the defrosting is started timely only when the actual frost accumulation mass is large, which solves the problems of high energy consumption and poor fresh-keeping effect caused by the traditional control method of defrosting in advance or delayed defrosting, and improves the energy-saving and fresh-keeping effects of the air-cooled refrigerator.

The embodiments above are only the preferred embodiments of the present application and are not intended to limit the application. Any modifications, equivalent substitutions, improvements, etc., which are within the spirit and principles of the present application, should be included in the protection scope of the present application. 

1. A method, comprising: collecting a first fan speed of a fan of an evaporator of a refrigerator during a stable operation of the refrigerator; determining whether the first fan speed is less than or equal to a threshold speed; and performing a defrosting operation on the evaporator in response to the first fan speed less than or equal to the threshold speed.
 2. The method of claim 1, wherein a heater is employed to defrost the evaporator during the defrosting operation.
 3. The method of claim 1, wherein the collecting the first fan speed includes: allowing the fan to operate at a rated voltage, and determining the first fan speed by detecting a feedback signal of an electric control loop of the fan.
 4. The method of claim 1, comprising: after the defrosting operation is performed, collecting a temperature of the evaporator; determining whether the temperature of the evaporator reaches a threshold temperature; and stopping the defrosting when in response to the temperature of the evaporator reaches the threshold temperature.
 5. The method of claim 1, comprising: before collecting the first fan speed during the stable operation of the refrigerator, collecting a second fan speed and a third fan speed of the fan before and after a first time period, respectively; determining whether a difference between the second fan speed and the third fan speed is less than or equal to a threshold speed difference; and determining that the refrigerator is the stable operation in response to it is determined that the difference between the second fan speed and the third fan speed is less than or equal to the threshold speed difference.
 6. A refrigerator, comprising a refrigerator body, an evaporator, an evaporating fan, a defrosting assembly, and a controller, the controller including: a data receiver circuit that acquires a temperature of the evaporator and a fan of the evaporating fan; a determiner circuit configured to perform actions including; collecting a first fan speed of the evaporating fan during a stable operation of the refrigerator; determining whether the fan speed is less than or equal to a threshold speed; and determining a defrosting operation on the evaporator based on a result of the determining whether the fan speed R is less than or equal to the threshold speed; and a signal sender that controls the defrosting assembly to perform the defrosting operation determined by the determiner circuit, wherein the defrosting operation include starting defrosting, not starting defrosting, continuing defrosting, or stopping defrosting.
 7. The refrigerator of claim 6, wherein the evaporating fan is disposed in an air duct of the refrigerator body; and the controller is connected with the evaporating, fan and the defrosting assembly through an electric control circuit, respectively.
 8. The refrigerator of claim 7, further comprising an evaporator sensor electrically connected with the controller and configured to detect the temperature of the evaporator; wherein during the defrosting operation performed by the defrosting assembly, the controller determines whether the defrosting assembly stops the defrosting operation based on the temperature of the evaporator detected by the evaporator sensor.
 9. The refrigerator of claim 7, wherein the defrosting assembly includes a heater arranged at a bottom of the evaporator.
 10. A computing device comprising a memory, a processor, and computer programs stored on the memory and executable by the processor, wherein the processor is configured to, when executing the computer programs, perform actions including: collecting a first fan speed of a fan of an evaporator of a refrigerator during a stable operation of the refrigerator; determining whether the first fan speed is less than or equal to a threshold speed; and control a defrosting assembly of the refrigerator to perform a defrosting operation on the evaporator in response to the first fan speed is less than or equal to the threshold speed. 11-12. (canceled)
 13. The computing device of claim 10, wherein the collecting the fan speed includes: allowing the fan to operate at a rated voltage, and determining the first fan speed by detecting a feedback signal of an electric control loop of the fan.
 14. The computing device of claim 10, wherein the actions include: after the defrosting operation is performed, collecting a temperature of the evaporator; determining whether the temperature of the evaporator reaches a threshold temperature; and stopping the defrosting when the temperature of the evaporator reaches the threshold temperature.
 15. The computing device of claim 10, wherein the actions include: before collecting the first fan speed during the stable operation of the refrigerator, collecting a second fan speed and a third fan speed of the fan before and after a first time period, respectively; determining whether a difference between the second fan speed and the third fan speed is less than or equal to a threshold speed difference; and determining that the refrigerator is the stable operation in response to it is determined that the difference between the second fan speed and the third fan speed is less than or equal to the threshold speed difference.
 16. The refrigerator of claim 6, comprising a compressor, a condenser, and a capillary tube, wherein the compressor, the condenser, the capillary tube, and the evaporator together constitute a refrigerant circulation loop, and the evaporator is disposed in an air duct of the refrigerator body 